With nearly 4,000 different kinds of plants represented in the Arboretum's living collections, every day presents rich opportunities to see something new. If you enjoy learning about plants and their unique characteristics, you can contribute to science as a participant in our Tree Spotters program. This citizen science project opens a window into the Arboretum's phenology: the timing of natural events, such as the leafing out and flowering of trees in the spring and changing foliage colors in the fall. Your observations will assist Arboretum scientists in their studies of the effects of a changing climate on plants. Attend a free training session. All levels of experience are welcome.